Liquid purification is the process of removing undesirable contaminants (e.g., salt; dirt; biological materials such as protozoans, bacteria, spores, or viruses; or other particulates) from a liquid. Liquid purification has become increasingly important in a variety of contexts. For example, water may be accessible but unfit for human consumption due to environmental pollution or naturally occurring phenomena (e.g., as with ocean water). Purification of the water may sanitize the water for human use or consumption. As another example, water used for an industrial application (e.g., for hydraulic fracturing) may become contaminated as a result of the industrial application. Purification of the water may allow it to be reused in other industries or for other applications, saving resources and reducing costs. However, it can be challenging to sufficiently purify liquids of contaminants.
At present, there are two primary methods for purifying liquids: thermal-based methods and membrane-based methods. Thermal-based methods typically involve heating a contaminated liquid until it vaporizes, leaving behind contaminants. The vapor is then cooled, returning the vapor to its liquid state. Membrane-based methods typically involve using high pressure to force contaminated liquids through a membrane (e.g., a filter). Contaminants are separated from the liquid via the membrane. However, both of these methods have significant disadvantages. For example, both methods are expensive. Thermal-based methods may require significant amounts of energy to vaporize the liquid during purification, and membrane-based methods may require significant amounts of energy and expensive membranes for purification. Further, both methods are inefficient and may damage the environment. Due to the practical limitations of thermal-based and membrane-based purification systems, 50% or less of the contaminated liquid input into these purification systems may be converted into pure liquid. The remaining contaminated liquid may contain its original contaminants plus the contaminants left behind from the purified liquid. The result is a highly-concentrated contaminated liquid by-product called “brine waste.” Often, brine waste may be discarded into streams or oceans, or otherwise disposed of in ways that can cause environmental problems. Further, properly disposing of brine waste may require navigating complex regulatory rules, and often requires expensive equipment (e.g., pumps, pipelines, and other facilities) for discharging the waste.
What is needed are environmentally-friendly, efficient, and cost-effective methods, systems, and apparatuses for purifying liquids.